Art of desiccating liquids



March 3, 1931. PEASE 1,794,978

ART OFDESICCATIN G LIQUIDS Filed June 9 1925 3 Sheets-Sheet lKali/726.29:

March 3, 1931. F. F. PEASE ART OF DESIGCATING LIQUIDS Filed June 9 19253 Sheets-Sheet 2 March 3, 1931. F. F. PEASE ART OFDESVICCATING mournsFiled June 9, 25 3 Sheets-Sheet 5 Patented Mar. 3, 1931 UNITED STATESPATENT OFFICE FRED FORREST PEASE, F SQUANTUM, MASSACHUSETTS, ASSIGNOR TOI. I. TEASE, INC., 01' BOSTON, MASSACHUSETTS, A CORPORATION OFMASSACHUSETTS ART 0! DESICCATING LIQUIDS Application filed June a,

The present invention relates to drying liquid and semi-liquid productsand more particularly to drying liquid products delivered to the dryingair in the form of a spray.

Various expedients have been suggested for drying liquids, such as milk,liquid soap, etc., sprayed into drying air for the purpose of removingthe water and collecting the remaining solid substance in the form of amerlo chantable product. Difiiculty has been experienced, however, inremoving the water from the liquid product and thereafter separating theproduct from the air without injury either to the product or withoutemploying a complicated or elaborate apparatus.

One object of the present invention is to provide a relatively simpleand compact apparatus for drying liquid products and recovering the dryresidue in a single operation and without injury to the product.

With this and other objects in view, one feature of the presentinvention contemplates delivering the liquid to be dried into'a streamof drying air from the lip or edge of a rotating nozzle in such a mannerthat the liquid is intimately associated with the dryin air withoutsubstantial contact with the wa is of the container.

A further feature of the invention contemplates means for maintainingthe drying air and entrained liquid in continuous motion throughout thedrying chamber and thereafter permitting a substantially free passage ofair with entrained liquid from the chamher while forcibly separating thedried residue therefrom.

Still further features of the invention consist in certain novelfeatures of construction, combinations. and arrangements of partshereinafter described and claimed, the advantages of which will beobvious to those skilled in the art from the following description.

In the accompanying drawings illustrating the preferred form of theinvention in its apparatus aspect, Fig. 1 represents a longitudinalsection in elevation of the drying apparatus embodying the features ofthe invention; Fig. 2 is a detail illustrating a par- 60 tial frontelevation of the apparatus; Fig. 3

1925. Serial No. 35,884.

is a detail illustrating a sideelevation partly in section of the meansfor spraying liquid into the drying air and for deliverin air to thechamber; and Fig. 4 is a detail s owing the air seal for the separator.

In the embodiment of the invention il1ustrated'in the drawings asubstantially cylindrical drying chamber 10 is provided with means atone end for delivering liquid and drying air thereto and at the oppositeend for separatin the dried residue from the air. The cylindrical dryingchamber may have a length approximating three or more times thediameter. The liquid substance to be dried is delivered into one end ofthe chamber at approximately the axis in the form of a funnel shapedspray which immediately encounters the drying air. The direction of theliquid in the air is such that the liquid is caused to intimatelyassociate with the air without impingin on the adjacent walls of thecontainer or ecoming immediately subjected to an excessive volume of hotdry air, which would cause the immediate formation of a dry residue onthe walls of the container adjacent the delivery point of the liquid. Inactual practice, the drying of the liquid is progressive and uniform asit traverses the length of the drying chamber and is substantiallywholly completed when the air and entrained substances reach theopposite end of the chamber and encounter the means for separating andrecovering the dry residue.

As indicated more particularly in Fi s. 1 and "3, a nozzle 20 projectsinwardly rom an end wall 22 of the container. This nozzle 7 isdetachably connected by screws 24. with a hollow supporting head 26mounted in the wall 22 as indicated. Journaled within the nozzle andprojecting slightly beyond the inner edge of the nozzle is a rotaryatomizing cup 28 supported upon the end of'a tubular enclosed by an endcasting 40. The cup is rotated through the pulley in any convenientmanner as by an electric motor, not shown, which may be connected to thepulley through a belt. Supported concentrically within the rotating cupis a feed tube 42 having an inner down turned delivery end 44, whichfeeds the liquid on to the bottom of the cup back of the outer deliveryedge. This feed tube is supported within the end castin and isadjustably secured in place by a t umb screw 46 which permits theposition of the delivery end to be varied with respect to the interiorof the cup. The feed tube is connected with a liquid storage tank 50through a connecting pipe 52 and valve 54. The storage tank. contalnsthe liquid-to be dried, the flow of which may be regulated through*ately engaged by air emerging from the nozzle about'the cup, whichdiverts the spray of liquid and causes it to flow outwardly in agenerally funnel shaped stream. In addition to the air sup lied about.the rotary cup 28 air in materially larger volume is suphed about thenozzle through a duct 70 as indicated more particularly in Figs. 2 and3.

This air passes through a heater indicated at 72 andhas capacitycomparatively large quantity of liquid. Operating in con unction withthe two sources of air supply previousl mentioned 4 is a third currentof air supplie 'to the conical end wall 7 6throu h an air duct 78 whichentersthe conical en wall from the outside nearly tangentially, theelongate orifice dotted lines, at 78 cointherem, shown in cidin with thesimilarly shaped terminus .Of-Sflld duct 7 8. This air duct, asindicated in Figs 1 and 2, is designed to suppl air tangentially to thecontainer, the com inatlon of the two air currents serving to cause aspiraling movement of the entire body of air with entrained liquid in adirection lengthwise of the container. The air duct 78 is also connectedwith the heater 72, which serves to suplpl heated drying air deliveredthrough bot t e ducts 7 8 and 70. The control of the drying air in thismanner serves to remove moisture from the liquid substance and maintainthe substance to be dried out of contact with the walls of the containeruntil substantially all of the liquid hasbeen exposed by the air. Thisprevents incrustmounted in a similar 'a discharge passage 104.

action initiated by the for absorption of a ing the walls of thecontainer by partially dried substances and permits the recovery ofsubstantially all of the dried residue. Any small percentage of thedried residue which contacts and remains on the inner wall of thecontainer may be readily removed therefrom in its dry, granular orpowdered state. After its traverse throughout the length of thecontainer, the air with the dry residue carried thereby encounters arapidly revolving separator 90, which comprises a tubular screen baskethaving a mesh suited to the degree of fineness of the dried residue.

. The exit of the drying chamber is completely closed except through thescreen 90 and all of the drying air is compelled to pass therethrough.--This separator screen, as indicated moreparticularly in Fig. 1,consists of a slightly conical member closed at the inner end 92 andmounted upon a shaft 94 which is journaled at its opposite ends inbearings 96 and 98. The inner bearing 96 is supported in a skeletonspider 100' mounted within the container in such a manner as not tointerfere with the flow of ai r therethrough and the outer bearing 1sspider 102 enclosed in The basket is revolved at high speed from apulley 106 sup-- ported outside of the casing 104- and driven in anysuitable manner. The casing 104 com-. municates with a discharge duct108 connectedwitha blower of ample capacity to maintain the desired flowof air through the container. The dried residue either through directcontact with the surface of the rapidly revolving screen or throughcentrifugal screen is discharged from the air and collects in majorportion in a receiving pocket 110' formed in the lower portion of thecylindrical container beneath the separator me her.

It is very-important that leakage of. air laden with solidmaterialhetween the revolving se arator and the ed e of the casingshallbe e ectually prevente This is accomplished in the present invention ina unique and practical manner by providing fora counter-current of airbetween the outer edge of the separator and the adjacent wall of thecasing. To this end, as shown more particularly in Figs. 1 and 4, theouter edge of the screen basket is supported on a ring 120 having anoutwardly extending flange 122 which is substantially cent to thestationaryarallel to and adja- Eange 124 forming a part of the casing.The flange 122'is provided with blades 126 preferably cast thereon andadapted to insure a current of air in the direction of the arrow inFig. 1. With this construction, the rotation of the separator causes theblade 126 to act as'a .fan and introduce clean air from beyond theseparator back into the main drying chamber. This countercurrent of airis suflicient to efl'ectually prevent leakage of dust laden air from thedrying chamber into the exhaust passage and dis )enses with thenecessity of packing joints an similar devices for closing the openings.

If desired, in order to conserve heat, the exterior of the cylindricaldrying chamber may be covered by a layer of heat insulating material112, such as asbestos packing or similar material.

The present invention provides an eflicient and self-contained apparatusfor effectually drying and recovering materials originally in a liquidform. In actual practice, the

drying chamber enclosed by the casing has a diameter approximating sixfeet and a length of sixteen feet and is employed for drying liquidhemoglobin and liquid blood serum. The apparatus as employed for thispurpose effectually dries and recovers the serum and hemoglobin in agranular merchantable form without oxidizing or causing incrusting onthe the walls of the container or moving parts. By utilizing the currentof relatively cool air about the atomizing cup, the latter is maintainedcool and incrustation upon the walls of the cup prevented. In dryingcertain other liquid products, it may be possible to dispense with thecurrent of relatively cool air about the cup and heat the air for thispurpose.

Although the apparatus as illustrated and described is particularlydesigned for the spray drying of products originally in a liquid form,it will be nevertheless obvious that the apparatus could be employed, ifso desired, for cleaning or washing dirty air by spraying into the dirtyvair Washing liquid which would moisten and agglomerate the solidparticles and permit them to be separated.

The character of the liquid spray delivered from the front edge 62 ofthe atomizing cup may be varied by altering the position of the deliveryend 44 of the feed tube 42 lengthwise of the interior of the cup. 13suitably ad justing the position of the eed tube, the spray may begoverned to cause a thorough intermingling with the drying air and yetnot penetrate the surrounding envelope of air in a manner to engage withand form incrustation on the wall of the container. The control of theliquid spray in this manner is an important and desirable adjunct ofthis class of apparatus.

It will be evident to those skilled in the 'art that with this form ofappartus the drying of the liquid product'is uniform and continuousthroughout the length of the drying chamber. This is due in part to thefact that the liquid spray, as delivered, encounters the entering mainstream of drying air when said drying air is hottest, and is thereafterdi-- rected concurrently with the direction of air flow, being removedfrom objectionable contact with the walls of the drying chamber airdelivered'tangentially to the inner wall of the chamber and spiralingthereabout in a lengthwise direction. Furthermore, the employment of asubstantially horizontal drying chamber with the product supportedtherein during its traverse lengthwise of the chamber, precludes theprecipitation of', a part of the dried material to the bottom of thedrying chamber as frequently happens with a vertical chamber in whichthe movement of the product during the drying period is downward andconcurrent with the flow of drying air. In drying liquidsolutions suchas blood, milk or liquid soap, the use of the heated drying airinevitably produces dried hollow particles or granules which may beaccompanied by a certain degree of swelling or enlargement of the driedparticles or granules, probably dueto the initial and superficial dryingof the liquid drops with a subsequent expansion and evaporation ofmoisture from the interior, these materials having a composition such asto resist complete fracture of the granules into a powdered form duringthe progress of the drying action. The resulting product ischaracterized by an interior void or voids, may be described as granularrather than powdered, and due to a comparatively large superficial areais more readily soluble than would be a product not so constituted.Obviously such a product, if not subsequently powdered or ground into apowdered state, bulks larger than a finelydivided powder.

I claim: .1. The process of producing a dried product from liquidsolutions of materials such as blood, milk or soap, in an enclosedtreating space, which comprises the preparation of the material in theform of liquid stock, forcibly centrifugally spinning the liquid stockradially in all directions from a central and generally horizontal axis,projecting an annular current of gas about and in proximity to thedelivery region of the spray, the current of gas having a direction andvelocity such that it intercepts and diverts the spray and continuestherebeyond in a generally axial direction, supplying a further volumeof drying gas annularly about the central axis and the first mentionedcurrent and projected generally in an axial direction such that the twocurrents of gas with the combined s ray continue with a like manner offlow, w ich persists in a well defined axially-moving column entrainingthe gas-borne spray in process of drying, supplying a further current ofas in proximity and tangentially to the wal of the treating space in amanner to coact with said first named currents to entrain and propelspirally and axially spray parthrough the surrounding envelope of heatedblood, milk or soap,

completed, and subsequently separating dried particles from the gas.

2. Apparatus for producing a dried product from liquid solutions ofmaterials suchas comprising an enclosed drying chamber, a rotary cupspray member at one end of the chamber for-spinning liquid stockcentrifugally and radially from a central and generally horizontal axis,means for projecting an annular current of drying gas about the spraymember with sufficient velocity to move it axially throu bout the lengthof the chamber in a well de ned and persisting stream, meansintermediate the rotary spray member and first. mentioned projectingmeans for directing upon and intercepting the spray with an annular gascurrent mov- 1n me ntioned current and diverting the spray into agenerally axial direction the combined gas currents and entraine sprayto be propelled axially throughout the chamber in a well definedstreamwhich mailitains the spray gas borne until completion of drying,and means for thereafter separating the dried particles from the dryinggas.

3. Apparatus uct from liquid solutions of materials such as blood, milkor soap, comprising an enclosed drying chamber, a rotary cup spraymember at one end of the chamber for s mmng liquid stock centrifugallyand radia y from a central and generally horizontal axis, means for proecting an annular current of drying gas about the spray member withsuflicient veloc 1t to move it axially throughout the l h o the chamberin a well defined and persisting streamimmeans intermediate the rotarytraine spra mem r and first mentioned pro]ect-. ing means for directingupon and intercepting the spray with an annular gas current moving inlike manner of flow with the first mentioned current and diverting thespray into a generally axial direction ior causing the combined gascurrents and enspray to be propelled axially throughout the. chamber ina well defined stream which maintains the spray gas borne untilcompletion of drying, means for tengentially introducing a stream ofspray end of the chamber adjacent the wall thereof and outside saidannular current projecting means, and means for thereafter separatingthe dried particles from the drying gas.

In testimony whereof I have signed my. name to this specification. v

- FRED FORREST PEASE.

in like mannerof flow with the first 1 for causin for producing a driedprod-- gas at the v

